Ray Java RunManager hard code python

Hi all,
Currently we hard code “python” command here, but it is common that “python” command is for python2, and in that case we need to use “python3”. Some users may not have “python” and only have “python3”. Of course, this can be solved by creating a symbolic link or so, but UX would be better if we solve this inside Ray.

We can check if “python” exists, and if it exists we can check its version. We can use “python3” if necessary. However, users might want to use “python36” or so. So maybe we can add a config? Or is it enough?

Thanks

This should definitely be customizable, feel free to submit a Pull Request!